Vasco-occlusive coil with conical end

ABSTRACT

This is an implantable vaso-occlusive coil which is implanted using minimally invasive surgical techniques. It is a complex, helically wound coil made up of a primary helically wound coil which is then wound into a specific secondary shape. The secondary shape is itself a series of helical turns. At least a portion of the turns in the secondary shape form a cylindrical region and adjacent that region on at least one end is a conical region which tapers from a diameter approximating that of the central cylindrical region to a smaller diameter. The device is desirably self-forming upon exit from the distal end of a delivery catheter. Also, the conical tipped vaso-occlusive device may also utilize thrombus-enhancing filamentary material.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation application of U.S.application Ser. No. 09/038,468, filed Mar. 11, 1998, which is acontinuation application of U.S. application Ser. No. 08/774,504 filedDec. 30, 1996 (issued as U.S. Pat. No. 5,733,329 on Mar. 31, 1998), theentirety of which are incorporated by reference.

FIELD OF THE INVENTION

[0002] This invention is an implantable vaso-occlusive coil which isimplanted using minimally invasive surgical techniques. It is a complex,helically wound coil made up of a primary helically wound coil which isthen wound into a specific secondary shape. The secondary shape isitself a series of helical turns. At least a portion of the turns in thesecondary shape form a cylindrical region and adjacent that region on atleast one end is a conical region which tapers from a diameterapproximating that of the central cylindrical region to a smallerdiameter. The device is desirably self-forming upon exit from the distalend of a delivery catheter. Also, the conical tipped vaso-occlusivedevice may also utilize thrombus-enhancing filamentary material.

BACKGROUND OF THE INVENTION

[0003] Vaso-occlusive devices are surgical implements or implants thatare placed within some opening in the human body. Typically the openingis either within the vasculature or some other region which is to beoccluded. Such other sites include fallopian tubes and bile ducts. Theyare delivered typically via a catheter. It is intended that the deviceseither block the flow of blood through a vessel making up that portionof the vasculature via the formation of an embolus. An embolus may alsobe formed within an aneurysm stemming from a normal vessel by use ofthis invention.

[0004] One such widely used device is the helically wound vaso-occlusivecoil. Many such coils are dimensioned to engage the walls of the vesselsor other sites they are intended to occlude. Other significantly lessstiff helically wound devices have also been described in theliterature.

[0005] A patent describing an early vaso-occlusive device which patent,parenthetically, also provides an excellent background to thevaso-occlusive technology at that time is Ritchart et al. (U.S. Pat. No.4,994,069). Ritchart et al. describes a vaso-occlusive coil that assumesa linear helical configuration when stretched and a folded, convolutedconfiguration when released from the catheter. The stretched conditionis used in placing the coil at the desired site via passage through thecatheter. The coil assumes a relaxed configuration-which is bettersuited to occlude the vessel—once the device is released from thecatheter. Ritchart et al describes a variety of secondary shapesincluding “flower” shapes and double vortices.

[0006] The use of vaso-occlusive coils having attached fibrous elementsin a variety of secondary shapes is shown in Chee et al. (U.S. Pat. No.5,304,194). Chee et al. describes a helically wound device having asecondary shape in which the fibrous elements extend in a sinusoidalfashion down the length of the coil. These coils, as with the Ritchartet al. coils, are produced in such a way that they will pass through thelumen of a catheter in a generally straight configuration and, whenreleased from the catheter, form a relaxed or secondary shape in thelumen or cavity chosen within the human body. The fibrous elements shownin Chee et al. enhance the ability of the coil to fill space within thevasculature and to facilitate formation of an embolus and subsequentallied tissue.

[0007] There are a variety of ways of placing shaped and linear coilsinto the human vasculature. In addition to those patents which arebelieved to describe only the physical pushing of a coil out into thevasculature, (e.g., Ritchart et al.), there are a number of other waysto release a coil at a specifically chosen time and site. For instance,U.S. Pat. No. 5,354,295 and its parent U.S. Pat. No. 5,122,136, both toGuglielmi et al. describe a device which is electrolytically detachablefrom its pusher wire.

[0008] A variety of mechanically detachable devices is also known. Forinstance, U.S. Pat. No. 5,234,437, to Sepetka, shows a coil which ishelically unwound from a pusher having an interlocking surface. U.S.Pat. No. 5,250,071, to Palermo, shows an embolic coil assembly usinginterlocking clasps mounted both on the pusher and on the embolic coil.U.S. Pat. No. 5,261,916, to Engelson, shows a detachablepusher-vaso-occlusive coil assembly having an interlock ball andkeyway-type coupling. U.S. Pat. No. 5,304,195, to Twyford et al., showsa pusher-vaso-occlusive coil assembly having an affixed, proximallyextending wire carrying a ball on its proximal end and a pusher having asimilar end. The two ends are interlocked and disengage when the coil isejected from the distal end of the catheter. U.S. Pat. No. 5,312,415, toPalermo, shows a multiple coil device in which the coils are placed on asingle pusher in the form of a guidewire which has a section capable ofinterconnecting with the interior of the helically wound coil. U.S. Pat.No. 5,350,397, to Palermo et al., shows a pusher having a throat at itsdistal end and a pusher through its axis. The pusher sheath will holdonto the end of an embolic coil and the embolic coil will then bereleased upon pushing of the axially placed pusher wire against theproximal portion of the vaso-occlusive coil.

[0009] Vaso-occlusive coils having little or no inherent secondary shapehave also been described. For instance, in U.S. patent application Ser.No. 07/978,320, filed on Nov. 18, 1992, entitled “Ultrasoft EmbolismCoils With Fluid-Like Properties” by Berenstein et al. is coil havinglittle or no shape after introduction into the vascular space.

[0010] A variety of other patent applications assigned to TargetTherapeutics, Inc., of Fremont, California describe coils or otherrelated vaso-occlusive devices having specific shapes. Of particularinterest is U.S. design patent application Ser. No. 29/037,001 filedMar. 31, 1995 for spiral vaso-occlusive coils by Mariant et al.

[0011] None of these previously-described devices or self-forminghelically wound coils which self-form into secondary structures havingopposing conical end separated by a generally cylindrical portionbetween those opposing ends.

SUMMARY OF THE INVENTION

[0012] This invention is a vaso-occlusive device comprising a helicallywound coil which is formed by winding a wire into a first helix or form;the first helix is then itself wound into a secondary form. Thesecondary form is one which, once ejected from a delivery catheter,forms a shape having conical section at each opposing end, which conicalend diameter decreases to the furthermost points of the device. Itgenerally forms a “submarine” type shape. Desirably, the vaso-occlusivedevice is of a size and shape suitable for fitting within a vascularcavity (e.g., an aneurysm, perhaps, a fistula). Stiffness of variousparts of the coil may be tailored or selected to enhance the ability ofthe device for its specific applications. Fibrous materials may be woveninto the member or tied or wrapped onto it.

[0013] The device may be made in a variety of ways. Typically, themember is helically wound in a generally linear fashion to form a firstor primary winding. After completion of that step, the primary windingis then wound around an appropriately shaped winding fixture or form andthe so-wound assembly is heat treated to help it retain its shape afterremoval from the winding fixture. Auxiliary fibrous materials are thenadded by weaving, tying, or other suitable permanent attachment methods.

[0014] The device is used simply by temporarily straightening device andintroducing it into a suitable catheter, the catheter already havingbeen situated so that its distal opening is within the mouth of thevascular cavity or opening to be filled. The device is then pushedthrough the catheter and, upon its ejection from the distal end of thecatheter into the vascular cavity, assumes its relaxed shape.

[0015] The device is typically used in human vasculature to form embolibut may be used in any site in the human body or occlusion such as oneproduced by the inventive device is desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 shows a side view of a variation of the inventivevaso-occlusive device having but a single cone-shaped end and acylindrical center section.

[0017]FIG. 2 shows a side view of another variation of the inventivedevice having conical portions at each end.

[0018]FIG. 3 shows another variation of the inventive device in whichthe angles of the two conical ends of the device are substantiallydifferent.

[0019]FIG. 4 shows a cross section of the FIG. 3 device showing theinterior of fiber placement.

[0020]FIG. 5 is a close-up partial side view of a primary coil useful inthis invention showing tufted fibers.

[0021]FIG. 6 shows an electrolytically erodible joint useful indeploying this inventive vaso-occlusive device.

[0022]FIG. 7 is a partial cross section side view of a mechanicallydetachable joint suitable for use with this invention.

DESCRIPTION OF THE INVENTION

[0023] This invention is a vaso-occlusive device comprising one or morevaso-occlusive helical coils which are formed by winding a wire into afirst helix; the first helix is then wound into a secondary form. Thesecondary form may be held or restrained within a tubular body such as acatheter or introducer into a shape which approximates the shape of theinterior of that tubular body. The secondary form is one which, whenejected or pushed from the delivery catheter has a plurality of turns atleast one substantially conical portion adjacent to a centralcylindrical portion having a diameter approximating the larger end ofthe conical end. Preferably the device has opposing conical endsseparated by a cylindrical coil section.

[0024]FIG. 1 shows the most basic variation of (100) of the basicinventive device. In particular, vaso-occlusive device (100), has agenerally cylindrical section (102) also known as the mid-section (102)made up of a number of turns (103) helically wound of a primary coilwhich in turn was helically wound from a wire. The end section (104) hasa large end which continues on from the primary winding of centralsection (102) and creates a taper in section (104) and the taper becomessmaller and smaller as the axis of the coil proceeds. The coil may havea pitch (105) which is fairly loose, that is to say, that the distancebetween windings in the secondary shape are at least equal to thediameter of the primary coil making up those helical windings. This“looseness” prevents the coil from forming a fixed or pipe-like mass soreadily after it has been placed within the human body. This loosenessalso creates a secondary shape having a fairly large mass in thevasculature which decreases the length of the coil placed within thecatheter so to decrease the amount of friction encountered whendeploying the coil. A tightly wound coil producing the same deployedcoil volume may not be deployable because they simply refuse to bepushed through the catheter using normal pushing techniques. The loosewind discussed here is desirable but not required.

[0025] The angle of the coil (106) may be virtually any value between10° and approaching 90°. Indeed in some variations of the inventionwhich may be considered to be variations having non-conic ends, the endsection need only be a spirally wound disk.

[0026] The material used in constructing a vaso-occlusive member may beany of a wide variety of materials; preferably, the material chosen is awire of a radio-opaque material such as a metal or polymer. Suitablemetals and alloys for the wire making up the device (100) include thePlatinum Group metals, especially platinum, rhodium, palladium, rhenium,and other bio-compatible metals such as tungsten, gold, silver,tantalum, and alloys of these metals. These metals have significantradio-opacity and their alloys may be tailored to accomplish anappropriate blend of flexibility and stiffness. Highly preferred forthis service is a platinum/tungsten alloy.

[0027] The wire may also be of any of a wide variety of stainless steelsif some sacrifice of radio-opacity may be tolerated. Very desirablematerials of construction, from a mechanical point of view, arematerials which maintain their shape despite being subjected to highstress. Certain “super elastic alloys” include nickel/titanium alloys(48-58 atomic % nickel and optionally containing modest amounts ofiron); copper/zinc alloys (38-42% zinc); copper/zinc alloys containing11-10% by weight of beryllium, silicon, tin, aluminum, or gallium; ornickel/aluminum alloys (36-38 atomic % aluminum). Particularly preferredare the alloys described in U.S. Pat. Nos. 3,174,851; 3,351,463; and3,753,700. Especially preferred are the super elastic nickel titaniumalloys, particularly known as “nitinol”. These nickel titanium alloysare very sturdy alloys which will tolerate significant flexing withoutplastic deformation even when used as a very small diameter wire.

[0028] If a super elastic alloy such as nitinol is used in the device,the diameter of the coil wire may be significantly smaller than thatused when the relatively more ductile platinum or platinum/tungstenalloy is used as the material of construction.

[0029] The coils may be of radiolucent fibers or polymers (or metallicthreads or wires coated with radiolucent or radio-opaque polymers) suchas Dacron (polyethylene terephthalate or PET), polyglycolic acid,polylactic acid, fluoropolymers such polytetrafluoroethylene, or Nylon(polyamide), or even silk or cotton. Should a polymer be used as a majorcomponent of the vaso-occlusive member, it is desirably filled with someamount of a known radio-opaque material such as powdered tantalum,powdered tungsten, bismuth oxide, barium sulfate, and the like.

[0030] The coil material is first wound into a primary coil form. Theprimary coil is typically linear after it has been wound and heattreated. Generally speaking, when the device (100) is formed of ametallic coil and that coil is a platinum alloy or a super elastic alloysuch as nitinol, the diameter of the wire used in the production of thecoil will be in the range of 0.0005 and 0.006 inches. The wire of suchdiameter is typically then wound into a primary coil having a primarydiameter of between 0.005 and 0.025 inches. For most neurovascularindications, the preferable diameter is between 0.010 and 0.018 inches.The axial length of the primary coil will usually fall in the range of0.5 to 100 cm, more usually 2.4 to 40 cm. Depending on usage, theprimary coil may well have 10 to 75 turns per centimeter, preferably 10to 40 turns per centimeter. All of the dimensions here are provided onlyas guidelines and are not critical to the invention. However, onlydimensions suitable for use in occluding sites within the human body areincluded in the scope of this invention. The overall diameter of thedevice as deployed is generally between 3 and 25 millimeters with arange between 3 and 12 millimeters much more common. If this device isused within an aneurysm in the cranial vasculature, these shapes may betreated using devices having those diameters. Of course, such diametersare not a critical aspect of the invention.

[0031]FIG. 2 shows another variation of the inventive device (200). Inthis variation, the center section (202) is two or more times the lengthof the axial length of the conical end sections (204, 206). Thevariation (200) also obviously has two opposing ends or sections (204,206) which are helically wound and have an overall conical shape whichis smallest at the opposing extremities of the device. We have foundthat in some instances, it is desirable to provide a short “tail” suchas (208) on the end of the coil which last exits the delivery catheter.This tail (208) prevents the secondary coil turn from hanging in thecatheter mouth since the last portion of the device seen by the catheteris straight. The wire in this instance is continuous throughout each ofthe sections of the device.

[0032]FIG. 3 shows another variation (300) of the inventive device. Inthis variation, the central section (302) is quite short in axial lengthand has but little more than one turn of the coil in the secondary shapewithin central section (302). Terminal conical section (304) is,perhaps, three times the axial length of center section (302). Theopposing end section (306) is also quite short in axial length. Theangle of the cone in this variation is found in conical end (306) canapproach 90 degrees.

[0033] Also contemplated in this invention is the attachment of variousfibrous materials to the inventive device for the purpose of addingthrombogenicity to the resulting assembly. A wide variety of fibrousmaterials have been used in adding to the thrombogenicity of such coils.Including in this group are such well known materials as Dacron(polyethylene terephthalate), polyethylene, polypropylene, silk, Nylon,and cotton.

[0034] The fibrous materials may be added in a variety of ways, FIG. 4shows a cross section of the device shown in FIG. 3 and it shows thatthe fibrous materials (308) found therein are looped around in such away that they are continuous from end to end and generally may be tiedto the end of the coil. Another variation is had by tying the tuft orwrapping the tuft through the turns of the primary coil. Tufts may betied at multiple sites throughout the coil to provide a vast area ofembolus forming sites.

[0035]FIG. 5 shows a close up of a primary coil (310) having a number oftufts (312) passing through the primary turns of the coil and merelybeing held in place by turns of the coil itself.

[0036] The primary coil may be covered by a fibrous braid such as isshown in U.S. Pat. No. 5,382,259, issued Jan. 17, 1995, to Phelps andVan.

[0037] As was noted above, many vaso-occlusive coils are held in placebefore deployment in a variety of different ways so to provide a controlon the site and time of their deployment. Variations of the inventioninclude the use of electrolytic detachment joints such as is shown inFIG. 6 and mechanical detachment joints such as is shown in FIG. 7.

[0038] Specifically, the electrolytic joint shown in FIG. 6 is describedin significant detail in patent such as U.S. Pat. Nos. 5,122,136 and5,354,295, both to Guglielmi discussed above. In these variations, aninsulated pusher (402) is attached to the vaso-occlusive coil (404) viaan electrolytically erodible joint (406). A direct current is applied topusher (402). The current path is, in part, through joint (406) into theionic medium surrounding the coil upon deployment. Such ionic medium is,in the vasculature, blood or saline solution passing through thedeploying catheter. Joint (406) erodes and allows vaso-occlusive device(406) to remain in the body. Vaso-occlusive device (406) may be any ofthe devices described above with respect to this invention.

[0039] Similarly, FIG. 7 shows a mechanically detachable assembly (410)partially housed within a deployment catheter (412). The vaso-occlusivedevice itself (414) has an end clasp (416) which engages a similar endclasp (418) forming the end of pusher (420). When pusher (420) isforwarded distally so that both clasp (416) and clasp (418) are exteriorto catheter (412), the vaso-occlusive device (415) with its attachedclasp (416) is free to stay at the chosen site within the human body.Again, vaso-occlusive portion (414) may be any of the devices describedabove in relation to this invention.

[0040] In summary, the manner in which this device is employed ordeployed may be found in a variety of other prior publications. Inparticular, the reader is directed to Ritchart et al., discussed above.

[0041] Modification of the above-described variations of carrying outthe invention that would be apparent to those of skill in the fields ofmedical device design generally, and vaso-occlusive devicesspecifically, are tended to be within the scope of the following claims.

We claim as our invention:
 1. A vaso-occlusive device comprising a coilhaving a secondary structure, self-forming upon exit from a restrainingcatheter, said secondary structure having a substantially conicalportion, said substantially conical portion having a small end and alarge end, said large end adjacent a central cylindrical section.
 2. Thevaso-occlusive device of claim 1 wherein the secondary structurecomprises two opposing substantially conical portions each with a smallend and a large end and wherein each such large end is adjacent saidcentral cylindrical section.
 3. The vaso-occlusive device of claim 1where at least a portion of the secondary structure is helically woundand has a pitch, the coil has a diameter, and the secondary structurehas a pitch which is at least twice the coil diameter.
 4. Thevaso-occlusive device of claim 2 where at least a portion of thesecondary structure is helically wound and has a pitch, the coil has adiameter, and the secondary structure has a pitch which is at leasttwice the coil diameter.
 5. The vaso-occlusive device of claim 1 furthercomprising a plurality of fibers fixedly attached to said coil.
 6. Thevaso-occlusive device of claim 2 further comprising a plurality offibers fixedly attached to said coil.
 7. The vaso-occlusive device ofclaim 6 wherein the fibers comprise tufts.
 8. The vaso-occlusive deviceof claim 6 wherein the plurality of fibers are looped from turn to turnin said coil.
 9. The vaso-occlusive device of claim 1 wherein said coilhas at least one detachable end.
 10. The vaso-occlusive device of claim2 wherein said coil has at least one detachable end.
 11. Thevaso-occlusive device of claim 10 wherein the detachable end iselectrolytically erodible.
 12. The vaso-occlusive device of claim 10wherein the detachable end is mechanically detachable.
 13. Thevaso-occlusive device of claim 2 wherein the two opposing substantiallyconical portions adjacent said central cylindrical section are terminalon said device.
 14. The vaso-occlusive device of claim 1 wherein the atleast one conical portion further comprises a linear section of coiladjacent the small end of said at least one conical portion.
 15. Thevaso-occlusive device of claim 2 wherein at least one conical portionfurther comprises a linear section of coil adjacent the small end ofsaid at least one conical portion.